Richie McCaw may be in doubt for Friday night's encounter against the Blues at Eden Park.

The openside flanker is nursing a tender calf after the Crusaders' 18-10 loss to the Chiefs at Christchurch Stadium last weekend.

If he is ruled out of their second-round Super Rugby match against the Blues, Matt Todd will be awarded the No 7 jersey.

McCaw didn't participate in the warmups during training at Rugby Park today and Crusaders coach Todd Blackadder will be cautious about pushing the 33-year-old McCaw back too soon. Calf injuries can take an age to heal if aggravated.

Todd has always proved a capable performer at openside whenever McCaw has been unavailable in recent years. Although the All Blacks skipper remains without peer in his preferred position, he will not be risked if not fully fit.

Midfielder Ryan Crotty had his calf strapped and although he was in his gear he was a spectator at training.

"There are clouds over a few people who are in contention - Richie is straining a little bit, he has got a little bruise there and Ryan Crotty is not doing a full training today," Crusaders assistant coach Tabai Matson said.

"We got dinged up, as they [the Chiefs] did, so we are just taking a few days to recover."

First five-eighth Colin Slade, who was not considered for the side to face the Chiefs because of a calf complaint, should be available for selection if he proves his fitness.

Slade participated in the warmups and looked to be running without discomfort.

Blackadder will be keen to have him back after Tyler Bleyendaal missed five penalties against the Chiefs. He was replaced by Tom Taylor at halftime.

Captain and No 8 Kieran Read confirmed he was available to start after being rested from the Chiefs match.

If Crotty fails to recover, Taylor is likely to start at second five and Reynold Lee-Lo would probably remain at centre.